// 一、将下面异步代码使用 Promise 的方式改进

setTimeout(function() {
  var a = 'hello'
  setTimeout(function() {
      var b = 'lagou'
      setTimeout(function() {
          var c = 'I ❤️ U'
          console.log(a + b + c)
      }, 10);
  }, 10);
}, 10);
// ------------------------------------------------------
// 答案
function p(str){
  return new Promise(resolve=>{ resolve(str) })
}
async function output(){
  let a = await p('hello')
  let b = await p('lagou')
  let c = await p('I ❤️ U')
  console.log(a + b + c);
}
output()